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Posts: 1086
Location: Hayward, WI | Figured you musky nuts would like to see this stuff…
This information went out the clubs today, so feel free to distribute it.
Yesterday I received the genetic analysis results back from the musky captured in DNR surveys in Lake Wissota in 2015 and 2016. These samples were analyzed by the Molecular Conservation Genetics Laboratory at the University of Wisconsin-Stevens Point. Of the 156 musky tissue samples that were deemed suitable for analysis, four samples were determined to be pure Leech Lake strain and four samples were determined to be hybrids between Upper Chippewa River strain and Leech Lake strain musky.
The pure Leech Lake strain samples were from fish that measured 12.2”, 34.9”, 37.0” and 40.0” in length. The 12.2” fish had a fin clip and was captured during an electrofishing survey this spring while Joe Heil was on board and this fish was stocked last fall. The 40” fish was captured this spring on the Little Lake and was distinctly lighter in coloration, so this fish was carefully inspected for fin clips and none were found but photos were taken (attached). The 34.9” and 37” fish were captured in 2015 and had no fin clips upon capture. These fish were both males and their ages were both estimated at 10 years old making them from the initial stocking in 2005. How does the growth rates of these fish compare to the statewide average for musky? The average length of a 10 year old male musky in Wisconsin is 37.4”, so both of these Leech Lake strain fish are growing slower than the statewide average for male musky.
What do these results mean and what is their significance? First, fin clips appear to be a poor way of identifying older Leech Lake strain fish. I am still confident when the complete fin is removed, which has been done with the recent stockings, it will not grow back or be severely deformed making it distinguishable. Secondly, this data obliviously means that there is survival of Leech Lake strain fish in Lake Wissota. Musky stocked in Lake Wissota since 2005 have been stocked at a proportion of about 30% Leech Lake strain fish to 70% Upper Chippewa River strain fish. Everything being equal (survival, natural reproduction, capture rate) about 30% of the fish captured were expected to be Leech Lake strain fish. However, only four of the 156 samples analyzed were of Leech Lake origin which is a rate of 2.6%. This is much lower than expected and likely can be attributed to poor survival and not the lack of catchability which I will get into later.
The four hybrids between Upper Chippewa River strain fish and Leech Lake strain fish measured 11.4”, 12.4”, 15.2” and 36.2”. The three smaller fish ages were estimated at one and the 36.2” fish has not been aged yet because it was captured this spring. The significance of this is that there is natural reproduction of musky in Lake Wissota. This is new information and it has not been documented in the past. This also means that the Leech Lake strain fish are spawning with Upper Chippewa River strain fish meaning that they are using the same spawning habitat, so both strains should be vulnerable to our sampling gear. Because natural reproduction has now been documented in Lake Wissota, it will no longer be designated as a “universal receptor lake” and stocking of strains other than Upper Chippewa River strain will not be allowed. The reason why Leech Lake strain fish will not be permitted to be stocked is that their effect on the Lake Wissota musky population is not just limited to the life span of the fish, the genetic lineage of the Leech Lake strain may be a part of the population for many, many generations. Why does this matter? This matters because in other populations the progeny of introgression between different genetic strains have reduced the fitness of that population in terms of growth and survival and there can be long term negative consequences for population viability. Large scale impacts to the population are not anticipated because the number of hybrids at large is expected to be small, but now that there is documented natural reproduction, there is no reason put the future Lake Wissota musky population at additional risk.
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Posts: 462
Location: Madison Wi. Chain | Are you open to feedback and other interpretations of the data? |
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Posts: 1086
Location: Hayward, WI | Sorry, not my data. Just got an email today with the info and was passing it on. I know that Chippewa Falls Muskies Inc has put a lot of work and money into trying the LL strain. I was hoping that they would have taken off and created a big fish factory. |
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Posts: 32784
Location: Rhinelander, Wisconsin | That is written by Joseph Gerbyshak!
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Posts: 462
Location: Madison Wi. Chain | I think it is way too early to interpret the data. CCMI in Madison has been stocking for 11 years now in lake Monona. We plan on continuing to stock these fish. The LL strain are starting to show up, but have not differentiated themselves in size from the WI or Chip strain fish as of yet, but I don't think they have reached their top end potential. Gender of the fish makes a huge difference as males will typically be smaller. At noted above, some of the recapture could be male fish. Preliminary findings on Monona, suggest that size of the fingerlings and time of stocking makes a big difference. As fish greater then ten inches are more likely to survive. The other thing is that survival rates are low for all stocked fish. There are probably other variables such as food availability and fall and spring weather for each year class that create difficulties with recapture. I don't think the DNR will change their stocking practices, but have been willing to continue to allow CCMI to stock LL fish. So, if there are differences in overall size it takes a club that is committed to long-term stocking and follow up recapture. |
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Posts: 135
| I think you missed the key distinction: reproduction. This isn't a decision based on early interpretation of growth rates or survival such as your comments point to, nor is this a decision that First Wisconsin Muskies Inc is making. With any evidence whatsoever of successful reproduction in Wissota, the DNR is disallowing the stocking of non-native fish such as the Leech Lake strain. If similar intra-species muskie crosses, or even documented reproduction of pure Chippewa strain fish were to occur in Monona, the same risk would exist - that the DNR would stop Leech Lake strain from being stocked regardless of CCMI's commitment to their study.
Why did the DNR designate Wissota as a "universal receptor" lake and issue permits for Leech Lake strain as far back as 2005 (along with Petenwell and Monona) when at the same time the DNR was also designating it as a Class A1 (trophy) Category 2 muskie lake (some natural reproduction occurs, augmented by stocking). Back then either it shouldn't have been a Category 2 lake, or it shouldn't have been a "universal receptor." This new evidence suggests the Category 2 rating is accurate...and the error of allowing it to have been a "universal receptor" has wasted a lot of time, money, and emotion for both the DNR and First Wisconsin MI.
Notably, Petenwell and Monona are both Class A1 / Category 3 - trophy potential, no known reproduction.
http://dnr.wi.gov/topic/Fishing/documents/musky/WisconsinMuskellung...
Older versions of this booklet carry the same designations for Wissota.
Edited by Glaucus_ 8/4/2016 10:57 AM
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Posts: 1275
Location: Hayward, Wisconsin | This "study" still has not proven any natural reproduction of Chip River pure strain...and that's all I'm going to say on the matter. |
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Posts: 36
| A 50" L.L. was just caught in Madison along with many 48". This puts the growth rate of a L.L Musky in Madison to hit the 50" mark just a few years behind the greatest musky lakes in the world such as Vermillion. I'd say they are doing very fine
Edited by Jschinderle 8/14/2016 1:50 AM
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Location: MN | Have there been any studies done on this?
"This matters because in other populations the progeny of introgression between different genetic strains have reduced the fitness of that population in terms of growth and survival and there can be long term negative consequences for population viability."
I'm curious because the Lake Superior Chapter of MI is working with the local MN DNR to do a genetic and isotope study on fish in the St Louis River. The first year of data showed a lot of Leech Lake/Wisconsin strain hybrids. The SLR was stocked by MN and WI DNR's fish for several years which has resulted in a lot of hybrids. Are these fish likely to be inferior in some way compared to the pure strains? |
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Posts: 462
Location: Madison Wi. Chain | I was at the Muskies inc. symposium this spring. I attended a seminar on genetic diversity. The genetic differences among strains are actually very slight. So, I don't this that even in natural reproduction lakes introducing the LL strain will create much difference. In fact, maybe the lake will benefit from greater genetic diversity. BG |
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Posts: 32784
Location: Rhinelander, Wisconsin | http://en.metapedia.org/wiki/Inbreeding_depression_and_outbreeding_...
Avoiding outbreeding depression
The risk of outbreeding depression roughly increases with increased distance (genetic or geographic) between populations.[9]
Species in risk of extinction may also be threatened by inbreeding depression and outbreeding between different populations within the species is often advocated to avoid this. However, this instead risks causing outbreeding depression. A 2011 study recommended (based on both theoretical analysis of population genetics as well as empirical evidence) avoiding or be very cautious regarding crosses between two populations with characteristics such as being isolated from one another for more than 500 years or living in different environments.[13]
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I believe this is at least a rough concept of why Leechers are not readily stocked where NR is present.Given that hybrids are a reality in some waters already, maybe we can see what occurs long term. Love them spotted fish... |
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Posts: 2274
Location: Chisholm, MN | Moose Lake in Itasca Co MN has both Natural MN strain and Wisconsin strain fish. Or it did have WI strain at one time. Due to years of interbreeding, the lake very rarely puts out a 50 inch fish, so the DNR states. I would agree that it's a bad idea to mix stocking like that. |
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Posts: 1275
Location: Hayward, Wisconsin | MN Moose never did put out many big fish, even before they stocked WI strain there! |
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Posts: 2274
Location: Chisholm, MN | Larry Ramsell - 2/9/2017 8:11 AM
MN Moose never did put out many big fish, even before they stocked WI strain there!
That might be true, I couldn't tell ya. Too long ago for me. But our researchers say the genetics are all messed up because of it  |
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Posts: 1275
Location: Hayward, Wisconsin | What about the Shoepac mutts the MN DNR put in there before WI strain??? At least now the MN DNR knows to stock on PURE Mississippi River strain in all their lakes now! |
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Posts: 2274
Location: Chisholm, MN | Yeah, I forgot about those ones...3 strains in one lake! |
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Posts: 1275
Location: Hayward, Wisconsin | We should be so lucky to have only 3 strains in one lake here in WI!! Mutts for all... |
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Posts: 22
| Even with modest successful reproduction, MN lakes stocked with muskies the last 40 years have the threat of Shoepack ancestry in current populations. This is especially true of lakes that are no longer stocked. I lost the link, but there is a very good fisheries paper about Shoepack ancestry in Minnesota lakes.
One of my favorite lakes in N Minnesota has great trophy potential on paper (whitefish & tullibee forage and >3000 acres size) and the shoepack ancestry (and harvest) restrains this potential imho. I'm not a fisheries biologist, but this seems to be the logical explanation.
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